From 75a3b50ad9dc99ce9693a0086b968c6d3501db21 Mon Sep 17 00:00:00 2001 From: Krishna Chaitanya Chundru Date: Mon, 27 Jul 2026 19:32:36 +0530 Subject: [PATCH] PCI/ASPM: Use pcie_capability_clear_and_set_word() for ASPM disable/restore pcie_aspm_cap_init() disables ASPM L0s/L1 on both ends of the Link before touching L1SS config, then later restores the LNKCTL state that was in effect beforehand. Both steps use raw pcie_capability_write_word() calls: the disable step computes the new value by hand from a snapshot taken earlier in the function, and the restore step writes that same snapshot straight back. Switch both steps to pcie_capability_clear_and_set_word(), masked to PCI_EXP_LNKCTL_ASPMC, matching the accessor pcie_config_aspm_dev() already uses elsewhere in this file for the exact same register. This does a live read-modify-write of just the ASPM Control bits instead of relying on a stale snapshot for the rest of the word, and is consistent with how the rest of the file already touches this register. No functional change. Fixes: 7447990137bf ("PCI/ASPM: Disable L1 before disabling L1 PM Substates") Closes: https://lore.kernel.org/all/20260721143945.86E7D1F000E9@smtp.kernel.org/ Signed-off-by: Krishna Chaitanya Chundru Signed-off-by: Bjorn Helgaas Reviewed-by: Manivannan Sadhasivam Link: https://patch.msgid.link/20260727-aspm-v6-1-2ebb3ee7ef71@oss.qualcomm.com --- drivers/pci/pcie/aspm.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 172783e7f519..50ff78a62e8a 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -894,10 +894,10 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist) /* Disable L0s/L1 before updating L1SS config */ if (FIELD_GET(PCI_EXP_LNKCTL_ASPMC, child_lnkctl) || FIELD_GET(PCI_EXP_LNKCTL_ASPMC, parent_lnkctl)) { - pcie_capability_write_word(child, PCI_EXP_LNKCTL, - child_lnkctl & ~PCI_EXP_LNKCTL_ASPMC); - pcie_capability_write_word(parent, PCI_EXP_LNKCTL, - parent_lnkctl & ~PCI_EXP_LNKCTL_ASPMC); + pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_ASPMC, 0); + pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_ASPMC, 0); } /* @@ -927,8 +927,12 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist) /* Restore L0s/L1 if they were enabled */ if (FIELD_GET(PCI_EXP_LNKCTL_ASPMC, child_lnkctl) || FIELD_GET(PCI_EXP_LNKCTL_ASPMC, parent_lnkctl)) { - pcie_capability_write_word(parent, PCI_EXP_LNKCTL, parent_lnkctl); - pcie_capability_write_word(child, PCI_EXP_LNKCTL, child_lnkctl); + pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_ASPMC, + parent_lnkctl & PCI_EXP_LNKCTL_ASPMC); + pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL, + PCI_EXP_LNKCTL_ASPMC, + child_lnkctl & PCI_EXP_LNKCTL_ASPMC); } /* Save default state */